1. Field of the Invention
The present invention relates to a display device and a method of fabricating a display device, and more particularly, to an organic electroluminescent display (OELD) device and a method of fabricating an OELD device.
2. Discussion of the Related Art
Until recently, many display devices employed cathode-ray tubes (CRTs) to display images. However, various types of flat panel displays, such as liquid crystal display (LCD) devices, plasma display panel (PDP) devices, field emission display (FED) devices, and electro-luminescent display (ELD) devices, are currently being developed as substitutes for the CRTs. Among these various types of flat panel displays, the PDP devices have advantages of large display size, but have disadvantages of low lightness and high power consumption. Similarly, the LCD devices have advantages of thin profile and low power consumption, but have disadvantages of small display size. However, the OELD devices are luminescent displays having advantages of fast response time, high brightness, and wide viewing angles.
FIG. 1 is a cross sectional view of an OELD device according to the related art. In FIG. 1, an OELD 10 includes first and second substrates 12 and 28 facing each other and bonded together with a sealant 26. The first substrate 12 includes a transistor T, a first electrode 16 within a pixel region P, an organic emitting layer 18, and a second electrode 20. Each of the organic emitting layers 18 has red (R), green (G), or blue (B) emitting material layers. The first and second electrodes 16 and 20 together with the organic emitting layer 18 constitute an organic emitting diode. The second substrate 28 has a recessed portion 92 filled with a desiccant 94 for blocking entry of outer moisture.
In FIG. 1, when the first electrode 16 is formed of a transparent material, light emitted from the organic emitting layer 18 is transmitted toward the first substrate 12. Thus, the OELD is catagorized as a bottom emission-type OELD.
FIG. 2 is a view of an equivalent circuit for an OELD device according to the related art. In FIG. 2, a data line 49 and a gate line 36 cross each other to define a pixel region. In addition, the OELD device includes a power line 62, a switching transistor TS, a driving transistor TD, a storage capacitor Cst, and an organic emitting diode E. The switching transistor TS turns ON or OFF depending upon a gate signal supplied along the gate line 36. When the switching transistor TS is turned ON, a data signal is supplied to the driving transistor TD through the data line 49. Similarly, the driving transistor TD turns ON or OFF depending on the supplied data signal. When the driving transistor TD is turned ON, a power signal is supplied to the organic emitting diode E through the power line 62, and thus the organic emitting diode E emits light.
In FIG. 2, since the switching and driving transistors TS and TD and the organic emitting diode E are both formed on the first (lower) substrate 12 (in FIG. 1), production efficiency of the OELD device is reduced. For example, if one of the switching and driving transistors TS and TD and the organic emitting diode E is determined to be unacceptable after fabrication, then the first (lower) substrate 12 (in FIG. 1) is considered to be unacceptable, and thus the production efficiency of the OELD device is reduced. Furthermore, when the first electrode of the organic emitting diode E is formed of a transparent material, the OELD device functions as the bottom emission-type OELD. Accordingly, since the switching and driving transistors TS and TD and metal lines block bottom emission of the light, aperture ratio of the OELD device is reduced, and high resolution is difficult to achieve.